Piezoelectric valves are known in diverse configurations, for example from DE 2511752 A1, DE 3400645 A1, DE 3527069 A1, EP 0404082 B1, EP 0538236 A1, DE 4320909 C1, DE 4410153 C1, WO 97/09555 A1, DE 19547149 A1, EP 0191011 B1 and EP 0565510 B1. Piezoelectric valves belonging to the class in question and containing a piezoelectric bending element which, in view of the smallest possible leakage in closed position, is provided at least in the region opposite the nozzle with padding of an elastically resilient material, are described in particular in EP 0907852 B1 and EP 0943812 A1. According to EP 0907852 B1, the first of these citations, this padding of elastically resilient material is fashioned as an elastomeric disk attached locally to the bending element and made, for example, of fluorosilicone. According to EP 0943812 A1, there is applied on the freely movable region of the piezoelectric bending element located outside the clamping point an elastomeric coating, which is provided at the end face with a sealing bead, which ensures sealing of the inner chamber of the housing relative to the outside.
Compared with most other valves that can be activated electrically, piezoelectric valves are distinguished by particularly fast switching dynamics, which make this type of valve seem particularly suitable for a large number of applications. Nevertheless, the typical force-displacement characteristic of the bending transducer (in this regard, see in particular DE 4410153 C1) imposes certain limits on the application of piezoelectric valves, because the possible closing force decreases with increasing deflection. This typically limits the fluidic power that can be switched by the piezoelectric valve, which power is proportional to the product of flow to be switched and pressure gradient to be switched.
Accordingly, the object of the present patent application is to provide a piezoelectric valve of the type indicated hereinabove having increased fitness for practical use, with which valve higher switching powers can be achieved in practice than with known piezoelectric valves of the class in question, while still retaining or even improving the known advantages, such as the fast switching dynamics in particular.